It is known to provide a common lubricant pump for a number of lubricating points; the pump is electromagnetically actuatable in pulses and respectively discharges a predetermined amount of lubricant. A lubricant supply container is connected to the lubricant pump on the suction side; connecting devices for lubricant pipes which lead to the individual lubricating points can be selectively supplied with lubricant from the pressure side of the lubricant pump; an electric control device controls, in predetermined manner, supply of the lubricant to the lubricating points with respect to time.
The needle drive, including cam parts of knitting machines, requires constant lubrication. Likewise, the needle guides in the needle bed or cylinder need to be lubricated. Perfect, regular lubrication is of very great importance, particularly in modern, high-speed knitting machines. For this reason, these machines are often equipped with pressure oilers or pressure oil lubricating systems which from a central point supply pressurized oil through corresponding pipes to the individual lubricating points.
In a pressure oil lubricating device known from French Patent 1 094 985 a pulsed, electromagnetically actuated reciprocating pump is connected on the pressure side via pipes containing check valves to several lubricating points. The piston stroke of the lubricant pump can be changed in order to change the amount of lubricant conveyed per stroke. This device cannot ensure that all lubricating points will be supplied with identical amounts of lubricant. Since the lubricant pipes are connected in parallel to the pressure side of the lubricant pump, the amount of lubricant supplied to the individual lubricating points depends, among other things, also on the line flow resistance to the respective lubricating point. In another pressure oil lubricating device, in particular for knitting machines, known from German published patent application 36 24 982, an oil pump is provided in the form of an electromagnetically actuatable vibratory or oscillating piston pump. This oil pump is connected on the suction side to an oil supply container and its pressure pipe branches off into several branch pressure pipes each of which can be opened and closed by an electromagnetic valve. Each of these branch pressure pipes leads to an oil distributor chamber to which several oil supply pipes leading to the individual lubricating points are connected via check valves. The drive of the vibratory piston pump and successive opening of the electromagnetic valves can be automatically and arbitrarily activated by a control device comprising a programmable microprocessor. Since several oil supply pipes are connected to each oil distributor chamber, in this case too, it is not ensured that each lubricating point will necessarily receive the same amount of lubricant per piston stroke of the vibratory piston pump.
Uniform oil supply is ensured in an oil lubricating system, in particular for knitting machines, known from Germany Patent 29 36 374, in which each lubricating point has a piston pump of its own and an electronic circuit for controlling the respective drive associated therewith. Several piston pumps with their electronic circuits and an oil supply container can be united to form one structural unit. In high-feed knitting machines with a substantial number of lubricating points, the cost involved in a large number of individual piston pumps required fro this system is high.